Anticodon loop

What are the modified bases for tRNA?

What is the function of mRNA in DNA transcription?

photocopy of a gene (has sequence that is complimentary to 1 DNA strand and identical to other strand) ➡️ carries the info stored in DNA in nucleus to cytoplasm (for translation)

7

What is the start codon in mRNA to initiate translation?

What are the stop codons in mRNA to terminate translation?

Start codon: AUG

Stop codons: UAG, UGA, UAA

8

What makes prokaryotic mRNA different from eukaryote mRNA?

Polycistronic (polygenic): carry info for synthesis of several polypeptides from 1 mRNA

9

How is the timing of transcription and translation different in prokaryotes compared to eukaryotes?

Prokaryotes: transcription and translation are coupled (happens at the same time, since mRNA does not have to be stable)

Eukaryotes: transcription and translation happen separately

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What makes mRNA in eukaryotes different from mRNA in prokaryotes?

1) Has info for only 1 polypeptide2) it is heterogeneous nuclear RNA (hnRNA) = has introns & exons3) goes through post-transcriptional modifications4) transported to cytoplasm for translation

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What are the post-transcriptional modifications eukaryote mRNA goes through?

What is the main purpose of these modifications?

5' CappingPoly A tailingSplicing (alternative splicing, RNA editing)

Give mRNA stability, protection, ⬆️ lifespan

12

What is the function of small nuclear RNA (snRNA)?

Mediate the processing of primary transcripts (large precursor molecules formed from DNA transcription of genes for mRNA, tRNA, and rRNA) in nucleus ➡️ produces functional molecules for export to cytosol

13

In what direction does an RNA chain grow?

What enzyme initiates RNA synthesis? Is a primer needed?

'5 to 3' direction

RNA polymeraseNo primer needed

14

What are 4 features specific to transcription (differ from DNA replication)?